I just got my wiim amp pro. Everything works as expected. However while playing a dolby 5.1 from my xbox, I noticed that there's no LFE signal coming out of my subwoofer. In other words, I seem to get a 5.0 downmix, not a 5.1 one. This is not what happens with the sonos amp I have here (connected exactly the same way). Is there a setting I've missed? Thanks.